body {
    margin: 0;
    font-family: Arial, sans-serif;
    font-size: 16px;
}

header, footer {
    background-color: #f1f1f1;
    padding: 20px;
    text-align: center;
}

main {
    display: flex;
}

.left, .right {
    flex: 0 0 50%;
    padding: 20px;
}

img {
    max-width: 100%;
    height: auto;
}

/* 媒体查询 */
@media screen and (max-width: 768px) {
    .left, .right {
        flex: 0 0 100%;
    }
    body {
        font-size: 14px;
    }
}